A novel by Creator/DianaWynneJones, based on the stories of ''Literature/TamLin'' and ''Thomas the Rhymer'', with a modern-day setting.
While staying at her grandmother's, Polly Whittaker wandered onto the grounds of an old neighbouring mansion, Hunsdon House, and met a man called Thomas Lynn, with whom she struck up a peculiar friendship. Together they created stories in which their alter egos were heroes - but soon things from their imaginary world became real (though not always as expected), and Tom's mysterious relatives persistently badgered Polly to stay away from him.
Now nineteen and preparing to leave for university, Polly has no memories of Tom or anything to do with him. But when she realizes so many bits of her life don't make sense, she slowly uncovers her hidden memories and becomes determined to find out what happened to her friend.
* DrivesLikeCrazy: Tom. It's established that he can get away with this because his life is protected from danger until it's time for Laurel to claim it.
* TheFairFolk: Laurel and Co.
* FatAndProud: When they are young teenagers, Polly admires Nina's body because it is curvier than her own. Towards the end of the book Polly also is somewhat plump.
* ForcedIntoEvil: Seb. Polly doesn't have much sympathy for him, but consider this: the first time she ever saw him was at a funeral for his own mother, who had been killed to help Laurel live even longer. He grew up knowing he was the second least valuable member of the family, and that if Tom wasn't there to die they would have no compunction about sacrificing him instead. Can you really blame him for not wanting to die?
* LaserGuidedAmnesia: Polly is manipulated into agreeing to forget about Tom. Subverted, though, as while they removed all her memories of him, they didn't (or perhaps couldn't) remove all the memories and knowledge he was linked to, leading to bits of information she couldn't have possibly learned anywhere and conflicting memories. These open the door to remembering Tom.
* MaybeEverAfter: The MindScrew ending leaves some readers confused about where Tom and Polly's relationship will go.
** Tom and Polly. They meet when she's a child, and he's old enough to have been married. Polly gets a bit of a crush on him as a teen, but they don't actually start a relationship till she's in college.
** Both Tom and Leslie were teenagers when the (actually ancient but physically twenty - thirty looking) Laurel took an interest in them. Justified, in that she has to ensnare men and use them to prolong her husband's life, and presumably it's easier to get them under her thumb if she starts young.
* MindScrew: Wait, ''what'' happens at the end again?
* OurDragonsAreDifferent: They're made of ''garbage''! [[spoiler:And Tom's friend Sam]].
* ParentalAbandonment: Polly. ''Twice''. Her mother sends her to live with her father, under the belief Polly is the reason for all her failed relationships. Her father's too cowardly to tell his girlfriend Polly's staying with them indefinitely, so he pretends it's only a short visit and then has her leave, with no way to get back home. Lucky for Polly [[RaisedByGrandparents her grandmother steps in]].
* ThePowerOfLove: The only way Tom (or any of the men Laurel targets) can be saved.
* PurpleProse: An in-story example - Polly writes like this until Tom gives her some rather odd tips to cure her "sentimental drivel".
* RewritingReality: Tom and Polly's stories have a slight tendency to come true.
* ShoutOut: To various literary works.
** The whole story is based on the ballad of Tam Lin.
** Tom scolds Polly for plagiarizing ''Literature/TheLordOfTheRings''.
* ThisIsReality: Part of Tom's criticism of Polly writing PurpleProse. Namely, he takes her to task of writing of a handsome man's back "rippling" and explains why the prose is sentimental drivel.
* WifeHusbandry: Tom has a fundamental role in Polly's development, something that's referenced in the book itself. They hook up in the end.